CNN  —  North Korea is expanding a weapons plant that manufactures missiles used by Russia against Ukraine, according to new research from a US-based think tank. The facility produces both KN-23 missiles (Hwasong-11A) and KN-24 missiles (Hwasong-11B), according to researchers at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies. Located in the country’s second-largest city, Hamhung, the factory has been visited several times by North